Dollars & Sense

Kevin Rutherford

A tale of two drivers says a lot about fuel use

| February 07, 2013

A recent caller to my radio show said he and his friend had just finished a two-month test of how their driving habits affect fuel mileage.

Tests like this are often meaningless because there are too many variables to make good comparisons, but these two, driving trucks of similar specs, did it right. Each tracked fuel mileage closely for 30 days, then they switched trucks. Without making any other changes, they tracked fuel mileage again for 30 days, minimizing the difference in the trucks.

It’s not unrealistic to see a spread of $16,000 a year in fuel costs between an operator who’s careless with driving habits and one who is diligently monitoring miles per gallon and constantly trying new ways to improve that key measurement.

The first driver, “Tom,” had a 30-day average of 7.71 mpg while driving his own truck. The second driver, “Ben,” had a 30-day average of just 5.83 mpg while driving his own truck.

Tom and Ben drove the other truck the same way that they always drove their own truck. They booked the same loads and weights as they had the previous 30 days. They drove in the same region, under similar weather conditions.

When Tom was driving Ben’s truck, the 30-day fuel mileage average increased to 7.17 mpg, a 23 percent increase over what Ben achieved driving it. At the same time, Ben’s 30-day fuel mileage average in Tom’s truck was 6.38 mpg, a 17 percent loss relative to Tom’s average in that truck.

To put the percentages into perspective, with Ben in his own truck his annual fuel bill would be $85,763 based on 125,000 miles and $4 per gallon. With Tom in Ben’s truck, his annual fuel bill would be $69,735, a savings of $16,028.

Even accounting for some variables, there was a solid 20 percent difference in fuel economy based on driving habits. Many callers to the show didn’t believe the results. However, industry tests have shown for years that the difference in fuel economy between the best drivers and the worst can be as much as 30 percent.

What habits account for such a wide spread? Typically it’s many things: speed, idling, cruise control, shifting, acceleration and deceleration, route planning and other aspects. In March, I’ll give you instructions on how such driving habits can enable you to improve your fuel mileage.

The first step toward better driving habits
To determine how much certain practices affect your fuel mileage, you need to track that number closely:

  • Establish a standard for your fill-up. Make sure the truck is level. Choose a spot at which you stop putting in fuel – the bottom of the filler neck, for example. Be consistent.
  • Write down your odometer miles for the first fill-up. The next time you fill up, write down the odometer and the gallons added.
  • Divide the gallons into the miles traveled since last fill-up to get miles per gallon.

For MPG trends to have meaning, make notes for each tank on what you’re doing differently, such as slower average speed or smoother acceleration or deceleration. Also note load weight, weather conditions, terrain and other external factors. Then analyze what affects fuel mileage.

Another approach is to use my free online tool at MyGauges.com. It will track your mileage on every tank, as well as 30-, 60-, 90-day and lifetime averages. You can enter information right from your smartphone.

  • Smitty, springfeild,mo

    Thank you for that info on the mpg. i really never knew the formula for it. and should hav being a driver for so long. as rookie its ok to ask others about mpg but driving for 17yrs didnt want to seem stupid so thank you.

  • http://www.facebook.com/ken.nilsen Ken Nilsen

    Most trucks today have the ability to give you fuel, cruise, and idle information per trip. I have a 2009 Prostar and it has the information system in dash. I pull the data every trip and have built a spreadsheet to track everything. It is easier than ever to be a better business operator.

  • http://www.montway.com/ Montway Auto Transport

    That’s a great test the drivers have done. We have talked to our drivers to really try to save fuel and to do this they need to track and analyze.
    Will surely pass the tips and recommend mygauges.com

    thanks!

  • Andrea Sitler

    One company I was at rewarded the top 2 drivers each month with the highest MPG. Small price to pay for the savings the company gained. It raised awareness for most drivers as they all tried to gain the reward pay. Good maintenance, tire pressure and many other factors such as fuel quality and what additives are used play a role in MPG as well.

  • Myron Lind

    These effects have been will documented and well known for many years. Perhaps the most interesting part of this article is the statement: “Many callers to the show didn’t believe the result”. Add to that those who just didn’t know, and I guess you have most of the trucking industry. It is actually pretty easy to make money in trucking–just treat it like a real business. My truck averages 8.5 mpg (–yes, averages–2005 Kenworth). I live in the mountains of Virginia.

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